I have a new M&P .40 Pro with the KKM conversion 9mm barrel. I am using factory M&P 9mm mags and have all kinds of problems with. I have tried about 4 mags of ammo using two different factory 9mm mags and experienced all three types of failures; failure to feed, failure to eject and double feeds. I haven't tried it yet with the .40 barrel and .40 mags and ammo. I never had this with my G22 conversion. Help!